摘要
川西高原露天矿山边坡面临强烈的干湿和冻融循环作用,为保障矿山边坡稳定性及评估边坡地下水渗漏风险,以高寒区某露天矿山边坡板岩为研究对象,开展其在干湿循环、气冻(空气中冻融)循环和水冻(水中冻融)循环等不同工况下板岩孔隙结构及渗透性演化规律研究。通过核磁共振和岩心渗透试验分析不同工况和不同循环次数下试样内部的孔隙度、孔径分布和渗透率,同时结合扫描电子显微镜试验观察裂缝孔隙等特征。引入损伤变量,分析揭示不同工况下试样循环次数、孔隙度和渗透率之间的变化规律。结果表明,随干湿、气冻和水冻循环次数增加,3组试样的孔隙度和渗透率逐步增加。40次循环后,3组试样的孔隙度从0.28%分别上升到0.33%、0.64%和0.66%,渗透率从2.7×10^(-3)mD(1 mD=0.987×10^(-15) m^(2))分别上升到2.9×10^(-3)mD、4.2×10^(-3)mD和6.4×10^(-3)mD,水冻循环作用下孔隙度和渗透率增长幅度最大。三种工况下试样的渗透率和损伤变量均呈非线性正相关,R^(2)由大到小依次为气冻循环组>水冻循环组>干湿循环组。该研究对川西高寒区露天矿边坡稳定性和保水开采提供了一定的工程指导价值。
The western Sichuan region is rich in mineral resources and is one of the areas with the most abundant resources of hard-rock lithium ores in China.Most mines in this region are located in seasonally frozen soil zones of alpine regions,characterized by large temperature fluctuations,intense rainfall,and high annual evapo⁃ration.The ecological and geological environment in the region is fragile,making the balance between resource development and environmental protection a major challenge.Open-pit mining exposes slope rocks to intense evaporation and significant temperature fluctuations over prolonged periods,creating conditions for dry-wet and freeze-thaw cycles.These cycles alter the internal pore structure and the permeability of rocks,further affecting slope stability and groundwater systems.Therefore,investigating the evolution of rock pore structure and perme⁃ability under different environmental conditions is critical.This study selected slate samples from an open-pit mine slope in the alpine region of western Sichuan.The samples underwent cyclic tests under three conditions,including dry-wet cycles,freeze-thaw cycles in air,and freeze-thaw cycles in water.Additionally,multiple ex⁃perimental techniques were employed,including nuclear magnetic resonance(NMR)testing,permeability test⁃ing,and scanning electron microscopy(SEM).NMR could nondestructively detect the porosity and pore size distribution of samples under different numbers of cycles and different working conditions.Permeability tests could directly measure changes in permeability,thereby investigating the influence of the number of cycles on the permeability of samples.SEM was used to observe microstructural changes,such as internal cracks and pores of the samples.To analyze and reveal the variation patterns among the number of cycles,porosity,and permeability under different working conditions,a damage variable based on porosity was introduced.The results showed that the porosity of slate samples gradually increased with the number of cycles under all condi⁃tions.After 40 cycles,porosity increased from 0.28%to 0.33%(dry-wet cycles),0.64%(freeze-thaw cycles in air),and 0.66%(freeze-thaw cycles in water),indicating that freeze-thaw cycles had a significant influence on the increase in porosity,with an especially pronounced influence on the internal small pore structure of the slate samples.Compared with freeze-thaw cycles in air,freeze-thaw cycles in water more easily induced the for⁃mation of microcracks.This was because the continuously supplied external water during freeze-thaw cycles pro⁃moted an increase in rock porosity and the formation of new cracks.Meanwhile,the permeability of the rock samples increased gradually with the number of cycles.After 40 cycles,permeability increased from 2.7×10^(-3)mD(1 mD=0.987×10^(-15) m^(2))to 2.9×10^(-3)mD(dry-wet cycles),4.2×10^(-3)mD(freeze-thaw cycles in air),and 6.4×10^(-3)mD(freeze-thaw cycles in water),indicating that freeze-thaw cycles had a greater influence on perme⁃ability than dry-wet cycles.Permeability and damage variables exhibited a nonlinear positive correlation.How⁃ever,under the three different working conditions,the R^(2) between permeability and damage variable varied slightly,with the highest R2 for freeze-thaw cycles in air,followed by those of freeze-thaw cycles in water and dry-wet cycles.This study provides practical engineering guidance for future mining activities and offers a scien⁃tific basis and theoretical support to assess slope stability and ecological environmental impact in the open-pit mines of alpine regions.
作者
胥品潮
王大国
路建国
尹力
刘云
XU Pinchao;WANG Daguo;LU Jianguo;YIN Li;LIU Yun(School of Civil Engineering and Geomatics,Southwest Petroleum University,Chengdu 610500,China;School of Mechatronic Engineering,Southwest Petroleum University,Chengdu 610500,China;Sichuan Provincial Institute of Territorial Ecological Restoration and Geological Hazard Prevention,Chengdu 610081,China)
出处
《冰川冻土》
2025年第4期977-989,共13页
Journal of Glaciology and Geocryology
基金
国家自然科学基金项目(42171108)
四川省科技计划项目(2024NSFSC2007)资助。
关键词
干湿循环
冻融循环
孔隙
渗透率
板岩
dry-wet cycles
freeze-thaw cycles
porosity
permeability
slate
